U.S. patent application number 13/684635 was filed with the patent office on 2013-06-20 for light-emitting device lamp.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. The applicant listed for this patent is SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to Ki-hong MOON, Yun-whan NA, Dae-yeop PARK.
Application Number | 20130155674 13/684635 |
Document ID | / |
Family ID | 48609947 |
Filed Date | 2013-06-20 |
United States Patent
Application |
20130155674 |
Kind Code |
A1 |
PARK; Dae-yeop ; et
al. |
June 20, 2013 |
LIGHT-EMITTING DEVICE LAMP
Abstract
A light-emitting device lamp includes a light-emission unit
including one or more light-emitting elements; a power circuit unit
supplying a power to the light-emission unit; a heat radiation unit
having the light-emission unit mounted therein and radiating heat
that is generated by the light-emission unit; and a housing
contacting and surrounding a portion of an outer circumference of
the heat radiation unit and transmitting heat generated by the
power circuit unit to the heat radiation unit.
Inventors: |
PARK; Dae-yeop;
(Hwaseong-si, KR) ; NA; Yun-whan; (Suwon-si,
KR) ; MOON; Ki-hong; (Suwon-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SAMSUNG ELECTRONICS CO., LTD.; |
Suwon-si |
|
KR |
|
|
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD.
Suwon-si
KR
|
Family ID: |
48609947 |
Appl. No.: |
13/684635 |
Filed: |
November 26, 2012 |
Current U.S.
Class: |
362/235 ;
362/249.01 |
Current CPC
Class: |
F21Y 2115/10 20160801;
F21K 9/23 20160801; F21V 29/89 20150115; F21V 29/87 20150115; F21V
29/507 20150115; F21V 3/02 20130101; F21V 17/164 20130101; F21V
29/773 20150115; F21K 9/00 20130101; F21V 3/062 20180201; F21V
29/506 20150115; F21V 17/12 20130101; F21V 3/061 20180201 |
Class at
Publication: |
362/235 ;
362/249.01 |
International
Class: |
F21V 29/00 20060101
F21V029/00; F21V 3/00 20060101 F21V003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 15, 2011 |
KR |
10-2011-0135769 |
Claims
1. A light-emitting device lamp comprising: light-emission unit
comprising one or more light-emitting elements; a power circuit
which supplies a power to the light emission unit; a heat radiation
unit, which comprises the light emission unit mounted therein and
radiates heat; and a housing which contacts and surrounds a portion
of an outer circumference of the heat radiation unit and transfers
heat generated by the power circuit to the heat radiation unit.
2. The light-emitting device lamp of claim 1, wherein the housing
is formed of a thermal conductive resin material.
3. The light-emitting device lamp of claim 2, wherein the thermal
conductive resin material is formed of a material in which heat
conductive fillers are distributed in a polymer.
4. The light-emitting device lamp of claim 1, wherein a
non-conductive layer is formed on a region of the housing which is
externally exposed.
5. The light-emitting device lamp of claim 1, wherein the heat
radiation unit is formed by coating heat emission pigments to one
from among a thermal conductive metal material and a resin
material.
6. The light-emitting device lamp of claim 1, wherein at least one
from among the heat radiation unit and the housing is coated with
black-based pigments.
7. The light-emitting device lamp of claim 1, wherein the heat
radiation unit comprises: a mount part in which the light emission
unit is mounted; a heat radiation body that is connected to the
mount part and surrounds a portion of the housing; and a plurality
of heat radiation pins that are disposed on a side of the heat
radiation body and are radially arrayed with respect to a central
axis of the light-emitting device lamp.
8. The light-emitting device lamp of claim 7, wherein the housing
comprises: a body contacting part that houses the power circuit and
contacts the heat radiation body; and a pin contacting part that is
connected to the body contacting part and that contacts and
surrounds portions of the plurality of heat radiation pins.
9. The light-emitting device lamp of claim 8, wherein one or more
grooves are formed in a top portion of the body contacting part,
and one or more through holes corresponding to the one or more
grooves are formed in regions of the mount part, whereby the body
contacting part and the mount part are combined by using at least
one screw.
10. The light-emitting device lamp of claim 8, wherein regions of
the plurality of heat radiation pins which contact the pin
contacting part are stepped, whereby an outer circumference of the
pin contacting part and outer circumferences of the plurality of
heat radiation pins are connected.
11. The light-emitting device lamp of claim 1, further comprising a
lamp cover that covers the heat radiation unit, and the heat
radiation unit comprises a cover contacting part that is formed on
an upper portion of the heat radiation unit and contacts a side
surface of the lamp cover.
12. The light-emitting device lamp of claim 11, wherein a coupling
groove to which the lamp cover is coupled is formed in the side of
the heat radiation body, and a projection coupled to the coupling
groove is formed on an end of the lamp cover.
13. The light-emitting device lamp of claim 11, wherein the lamp
cover comprises a radiation angle adjuster which adjusts a
radiation angle of light emitted from the light emission unit.
14. The light-emitting device lamp of claim 11, wherein the lamp
cover is formed of a light-transmitting material having a thermal
conductivity.
15. The light-emitting device lamp of claim 11, wherein the lamp
cover comprises a light-transmitting cover and one or more thermal
conductive layers that are formed on an outer circumference of the
light-transmitting cover.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATION
[0001] This application claims priority from Korean Patent
Application No. 10-2011-0135769, filed on Dec. 15, 2011, in the
Korean Intellectual Property Office, the disclosure of which is
incorporated herein in its entirety by reference.
BACKGROUND
[0002] 1. Field
[0003] Apparatuses consistent with exemplary embodiments relate to
a light-emitting device, lamp, and more particularly, to a
light-emitting device lamp having an improved heat radiation
performance.
[0004] 2. Description of the Related Art
[0005] In general, a light-emitting device such as a light-emitting
diode indicates a semiconductor device capable of realizing light
of various colors by forming a light-emission source via a P-N
junction of a compound semiconductor. The light-emitting device is
the semiconductor device that converts electric energy into light
energy, is formed as a compound semiconductor that emits light with
a particular wavelength according to an energy band gap, and is
widely used in optical communication, a display such as a computer
monitor, a back light unit (BLU) for a liquid crystal display
(LCD), lightings, or the like.
[0006] Recently, a light-emitting device lamp that replaces an
incandescent lamp is being supplied. However, the light-emitting
device lamp emits a large amount of light, such that it emits a
considerably large amount of heat radiation. Thus, a lifetime of
the light-emitting device lamp may be short unless the heat
radiation amount is efficiently controlled. In order to control the
heat radiation amount, heat radiation equipment such as a fan may
be mounted in the light-emitting device lamp. However, the
compulsory heat radiation equipment may cause an additional problem
such as an increase in material cost.
SUMMARY
[0007] Exemplary embodiments provide a light-emitting device lamp
having an improved heat radiation performance.
[0008] According to an aspect of exemplary embodiments, there is
provided a light-emitting device lamp including a light-emitter
comprising one or more light-emitting elements; a power circuit
which supplies a power to the light-emitter; a heat radiation unit
which has the light-emitter mounted therein and radiates heat that
is generated by the light-emission unit; and a housing which
contacts and surrounds a portion of an outer circumference of the
heat radiation unit and transfers heat generated by the power
circuit to the heat radiation unit.
[0009] The housing may be formed of a thermal conductive resin
material.
[0010] The thermal conductive resin material may be formed of a
material in which heat conductive fillers are distributed in a
polymer.
[0011] The heat conductive fillers may include at least one
particle selected from the group comprising carbon nanotube,
graphene, titanium oxide, zinc oxide, zirconium oxide, aluminum
nitride, and aluminum oxide.
[0012] A non-conductive layer may be further formed on a region of
the housing which is externally exposed.
[0013] The heat radiation unit may be formed by coating heat
emission pigments to one from among a thermal conductive metal
material and a resin material.
[0014] The heat emission pigments may include at least one material
selected from the group comprising ITO, SnO.sub.2, ZnO, IZO, carbon
nanotube, and graphene.
[0015] At least one from among the heat radiation unit and the
housing may be coated with black-based pigments.
[0016] The heat radiation unit may include a mount part in which
the light-emitter is mounted; a heat radiation body that is
connected to the mount part and surrounds a portion of the housing;
and a plurality of heat radiation pins that are disposed on a side
of the heat radiation body and are radially arrayed with respect to
a central axis of the light-emitting device lamp.
[0017] The housing may include a body contacting part that houses
the power circuit and contacts the heat radiation body; and a pin
contacting part that is connected to the body contacting part and
that contacts and surrounds portions of the plurality of heat
radiation pins.
[0018] One or more grooves may be formed in a top portion of the
body contacting part, and one or more through holes corresponding
to the one or more grooves may be formed in regions of the mount
part, whereby the body contacting part and the mount part may be
combined by using at least one screw.
[0019] Regions of the heat radiation pins which contact the pin
contacting part may be stepped, whereby an outer circumference of
the pin contacting part and outer circumferences of the plurality
of heat radiation pins may be connected.
[0020] The light-emitting device lamp may further include a lamp
cover that covers the heat radiation unit, and the heat radiation
unit may include a cover contacting part that is formed on an upper
portion of the heat radiation unit and contacts a side surface of
the lamp cover.
[0021] A coupling groove to which the lamp cover is coupled may be
formed in the side of the heat radiation body, and a projection
coupled to the coupling groove may be formed on an end of the lamp
cover.
[0022] The lamp cover may include a radiation angle adjuster which
adjusts a radiation angle of light emitted from the
light-emitter.
[0023] The lamp cover may be formed of a light-transmitting
material having a thermal conductivity.
[0024] The lamp cover may include a light-transmitting cover and
one or more thermal conductive layers that are formed on an outer
circumference of the light-transmitting cover.
[0025] The one or more thermal conductive layers may include at
least one material selected from the group comprising ITO,
SnO.sub.2, ZnO, IZO, carbon nanotube, and graphene.
[0026] The lamp cover may be formed of a light-transmitting ceramic
material of which thermal conductivity is equal to or greater than
9 W/mK.sup.-1.
[0027] The light-transmitting ceramic material may include at least
one material selected from the group comprising alumina, PLZT,
CaF.sub.2, Y.sub.2O.sub.3, YAG, polycrystalline ALON, and
MgAl.sub.2O.sub.4.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The above and other features will become more apparent by
describing in detail exemplary embodiments with reference to the
attached drawings in which:
[0029] FIG. 1 is an exploded perspective view of a light-emitting
device light-emitting device lamp according to an exemplary
embodiment;
[0030] FIG. 2 is a cross-sectional side view of the light-emitting
device lamp of FIG. 1;
[0031] FIG. 3 is a rear view of the light-emitting device lamp of
FIG. 1;
[0032] FIG. 4 is a cross-sectional view of an example in which a
housing and a heat radiation unit are combined in the
light-emitting device lamp of FIG. 1;
[0033] FIG. 5 is a diagram illustrating a contact structure between
the housing and the heat radiation unit in the light-emitting
device lamp of FIG. 1;
[0034] FIG. 6 is a cross-sectional view illustrating another
structure of the housing according to an exemplary embodiment;
[0035] FIG. 7 is a diagram illustrating a combination structure of
a light-emitting device cover and the heat radiation unit in the
light-emitting device lamp of FIG. 1;
[0036] FIG. 8 is a diagram illustrating a structure of the heat
radiation unit in the light-emitting device lamp of FIG. 1; and
[0037] FIG. 9 is a cross-sectional view of a lamp cover according
to an exemplary embodiment.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0038] Hereinafter, exemplary embodiments will be described in
detail with reference to the attached drawings. In the drawings,
like reference numerals in the drawings denote like elements, and
the size of each component may be exaggerated for clarity.
[0039] Expressions such as "at least one of," and "at least one
from among" when preceding a list of elements, modify the entire
list of elements and do not modify the individual elements of the
list.
[0040] FIG. 1 is an exploded perspective view of a light-emitting
device lamp 100 according to an exemplary embodiment. FIG. 2 is a
cross-sectional side view of the light-emitting device lamp 100 of
FIG. 1. FIG. 3 is a rear view of the light-emitting device lamp 100
of FIG. 1. The light-emitting device lamp 100 of FIGS. 1 through 3
is an example of an light-emitting device lamp (e.g., a PAR series
and an MR series) for replacing a halogen lamp.
[0041] Referring to FIGS. 1 through 3, the light-emitting device
lamp 100 includes a light-emission unit 10 including one or more
light-emitting elements 12, a heat radiation unit 30 having the
light-emission unit 10 mounted therein and radiating heat from the
light-emission unit 10, a power circuit unit 70 supplying a power
to the light-emission unit 10, and a housing 40 contacting and
surrounding an outer surface of the heat radiation unit 30 and
delivering heat, which is generated by the power circuit unit 70,
to the heat radiation unit 30.
[0042] The light-emission unit 10 may include the one or more
light-emitting elements 12 and a circuit substrate 14 on which the
one or more light-emitting elements 12 that emit light are mounted.
The light-emitting element 12 may be mounted on the circuit
substrate 14 in the form of a light-emitting device package formed
by packaging a light-emitting element chip by using a lead frame, a
mold frame, phosphors, and a light-transmitting filling material
according to a pre-mold method. Also, the light-emitting element 12
may be mounted on the circuit substrate 14 in the form of a
phosphor-coated light-emitting device chip according to a wire
bonding method or a flip-chip-bonding method. The circuit substrate
14 may include a metal substrate or a metal core so as to improve a
heat radiation performance.
[0043] The power circuit unit 70 supplies power to the
light-emission unit 10 and electrically connects the circuit
substrate 14 and a socket unit 50 that receives the power from an
external power source. A driving circuit (not shown) is formed in
the power circuit unit 70 so as to drive the light-emitting element
12 by using electric energy supplied via the socket unit 50. When
the power circuit unit 70 is driven, heat is also generated, and by
radiating the heat, the light-emitting device lamp 100 may have a
long lifetime.
[0044] The heat radiation unit 30 may function to externally
radiate heat that is generated by the light-emission unit 10 and
may have a shape that is exposed to air and has a large heat
emission area. For example, the heat radiation unit 30 may include
a mount part 31 in which the circuit substrate 14 having the
light-emitting element 12 is mounted; a heat radiation body 32 that
extends from the mount part 31 and is surrounded by a portion of
the housing 40; and a plurality of heat radiation pins 33 that are
disposed on the side of the heat radiation body 32 and that are
radially arrayed with respect to a central axis of the
light-emitting device lamp 100. The mount part 31, the radiation
body 32, and the heat radiation pins 33 may be formed as one
body.
[0045] The mount part 31 may have a round and flat plate shape. In
the mount part 31, one or more first through holes (not shown) via
which a wire (not shown) for connecting the circuit substrate 14
and the power circuit unit 70 passes may be formed. Also, in the
mount part 31, one or more second through holes (not shown) via
which a screw for fixing the heat radiation unit 30 to the housing
40 passes may be formed.
[0046] The heat radiation body 32 may have a cylindrical shape.
However, the cylindrical shape of the heat radiation body 32 is an
example and thus a shape of the heat radiation body 32 may be one
of various shapes including a polygonal-pillar shape.
[0047] Also, the heat radiation pins 33 that are radially arrayed
with respect to a central axis A of the light-emitting device lamp
100 may be disposed on the side of the heat radiation body 32. The
heat radiation pin 33 may have a partially oval shape portion that
may contact the heat radiation body 32 while vertically extending
from the heat radiation body 32. The plurality of heat radiation
pins 33 may be arranged.
[0048] The plurality of heat radiation pins 33 allow
high-temperature heat delivered from the light-emitting element 12
to the heat radiation body 32 to be conducted and then to be
externally radiated, by expanding a superficial area that contacts
air. In the radial array of the plurality of heat radiation pins
33, a density is lower in an open outer space than a compact space
of a central area, so that the radial array of the plurality of
heat radiation pins 33 may allow fast heat radiation according to a
principle in which high-temperature heat moves from a high-density
space to a low-density space.
[0049] The heat radiation unit 30 may be formed of a metal material
such as aluminum (Al), copper (Cu), or the like that have an
excellent heat conductivity. Alternatively, the heat radiation unit
30 may be formed of a resin material, other than the metal
material, which has an excellent heat conductivity. Also, the heat
radiation unit 30 may be formed by additionally coating heat
emission pigments to the metal material or the resin material. The
heat emission pigments may include at least one material selected
from the group comprising ITO, SnO.sub.2, ZnO, IZO, carbon
nanotube, and graphene. Also, the heat radiation unit 30 may be
coated with black-based pigments. By using the black-based
pigments, an effect of an easy thermal conductivity and heat
radiation may be achieved without separately arranging equipment or
incurring additional costs.
[0050] The housing 40 houses the power circuit unit 70 and is
connected to the heat radiation unit 30 and the socket unit 50. In
the present exemplary embodiment, the housing 40 and the socket
unit 50 are formed as one body but one or more exemplary
embodiments are not limited thereto. The housing 40 may include the
body contacting part 42 that houses the power circuit unit 70 and
contacts the heat radiation body 32, and a pin contacting part 44
that is connected to the body contacting part 42 and the socket
unit 50 while the pin contacting part 44 contacts and surrounds
portions of the plurality of heat radiation pins 33. One or more
first coupling grooves 73 to which the heat radiation unit 30 is
combined may be formed in a top portion of the body contacting part
42.
[0051] FIG. 4 is a cross-sectional view of an example in which the
housing 40 and the heat radiation unit 30 are combined in the
light-emitting device lamp 100 of FIG. 1. As illustrated in FIG. 4,
the first coupling grooves 73 are formed in the top portion of the
body contacting part 42, and the second through holes are formed in
regions of the mount part 31 which correspond to the first coupling
grooves 73. Thus, because a screw 77 is coupled to the first
coupling groove 73 via the second through hole, the body contacting
part 42 and the mount part 31 may be combined.
[0052] When power is supplied to the light-emitting element 12,
heat is generated not only by the light-emitting element 12 but
also generated by the power circuit unit 70 that drives the
light-emitting element 12. Thus, it is necessary to radiate the
heat generated by the power circuit unit 70. In order to deliver
the heat generated by the power circuit unit 70 to the heat
radiation unit 30, the housing 40 may be formed of a material
having a thermal conductivity. For example, the housing 40 may be
formed of a thermal conductive resin or the like. Also, the thermal
conductive resin may be formed of a material in which heat
conductive fillers are distributed in a polymer. The heat
conductive fillers may include at least one particle selected from
the group comprising graphene, titanium oxide, zinc oxide,
zirconium oxide, aluminum nitride, and aluminum oxide.
[0053] The heat generated by the power circuit unit 70 may be
delivered to the heat radiation unit 30 via the housing 40, a
maximally-increased contact area between the housing 40 and the
heat radiation unit 30.
[0054] FIG. 5 is a diagram illustrating a contact structure between
the housing 40 and the heat radiation unit 30 in the light-emitting
device lamp 100 of FIG. 1. As illustrated in FIG. 5, the body
contacting part 42 of the housing 40 contacts the heat radiation
body 32. Thus, heat generated by the housing 40 may be easily
transferred to the heat radiation unit 30.
[0055] The pin contacting part 44 of the housing 40 may contact the
heat radiation pins 33 of the heat radiation unit 30. As
illustrated in FIG. 5, an inner circumference of the pin contacting
part 44 may contact outer circumferences of the heat radiation pins
33. If the pin contacting part 44 covers too large a portion of the
outer circumferences of the heat radiation pins 33, external heat
radiation may be prevented. Thus, the pin contacting part 44 may
partially cover the outer circumferences of the heat radiation pins
33 while the partial coverage may minimize the external heat
radiation. Also, regions of the heat radiation pins 33, which
contact the pin contacting part 44, may be stepped, so that an
outer circumference of the pin contacting part 44 and the outer
circumferences of the heat radiation pins 33 may be continuously
connected. By doing so, a contact area between the heat radiation
pins 33 and the pin contacting part 44 may be maximally
increased.
[0056] Also, at least one non-conductive layer may be formed on a
region of the housing 40 which is externally exposed.
[0057] FIG. 6 is a cross-sectional view illustrating another
structure of the housing 40 according to an exemplary embodiment.
As illustrated in FIG. 6, a non-conductive layer 46 may be formed
on a region of the housing 40 which is externally exposed. As
described above, the housing 40 is formed of a thermal conductive
layer, so that heat generated by the power circuit unit 70 is
delivered to the heat radiation unit 30. However, because the
non-conductive layer 46 is formed on the externally-exposed region
of the housing 40, a user may easily manipulate the light-emitting
device lamp 100 while the light-emitting device lamp 100 generates
heat.
[0058] The light-emitting device lamp 100 may further include a
lamp cover 60 that covers the light-emission unit 10, including the
light-emitting element 12 and the circuit substrate 14. The lamp
cover 60 may be a cylindrical light-transmitting cover having an
empty inner space. Also, the lamp cover 60 may be a milky cover for
diffusion of light. In the lamp cover 60 according to the present
exemplary embodiment, radiation angle adjusting units 62 may be
formed to adjust a radiation angle of light emitted from the
light-emitting element 12. In the present exemplary embodiment, the
radiation angle adjusting units 62 are formed as lenses but one or
more exemplary embodiments are not limited thereto. For example,
although not illustrated, the radiation angle adjusting units 62
may be formed as reflecting units that radiate light that is
emitted from the light-emitting element 12 at a desired radiation
angle.
[0059] A projection 74 may be formed on an end of a side surface 64
of the lamp cover 60 of the light-emitting device lamp 100.
[0060] FIG. 7 is a diagram illustrating a combined structure of a
light-emitting device cover and the heat radiation unit 30 in the
light-emitting device lamp 100 of FIG. 1. As illustrated in FIG. 7,
the projection 74 having a screw shape may be formed on the end of
the side surface 64 of the lamp cover 60, and a second coupling
groove 75 to which the lamp cover 60 is coupled may be formed in a
top region of the heat radiation unit 30. The second coupling
groove 75 may have a complementary shape to the projection 74. In
this manner, the projection 74 of the lamp cover 60 is coupled to
the second coupling groove 75 of the heat radiation unit 30, so
that the lamp cover 60 and the heat radiation unit 30 are combined.
The combination method for the lamp cover 60 and the heat radiation
unit 30 is not limited to the aforementioned method, and thus
various methods including a snap-fit combination method may be
applied thereto.
[0061] For a lamp to have a high efficiency and a long lifetime
although an output of the lamp increases, it is necessary to assure
a sufficient heat radiation performance in a limited size and
shape. In this regard, in order to radiate heat generated by the
light-emitting element 12, the lamp cover 60 may be formed of a
material capable of radiating heat. In general, a thermal
conductivity of a glass material, a polycarbonate (PC)-based resin
material, and a polymethyl methacrylate (PMMA)-based resin material
is about 0.3.about.3 W/mK.sup.-1, which is considerably inadequate
for a material to radiate the heat generated by the light-emitting
element 12. In this regard, the light-emitting device lamp 100 may
include the lamp cover 60 that is formed of a light-transmitting
material of which thermal conductivity is equal to or greater than
9 W/mK.sup.-1. The thermal conductivity of the lamp cover 60 is
about 3 to 30 times higher than a thermal conductivity of a lamp
cover formed of a general transparent resin material.
[0062] Alternatively, the lamp cover 60 may be formed of a
light-transmitting ceramic material of which thermal conductivity
is equal to or greater than 9 W/mK.sup.-1. For example, an alumina
(Al.sub.2O.sub.3) molded body has light-transmittance and its
thermal conductivity is significantly higher than a thermal
conductivity of a general light-transmitting material. For example,
a thermal conductivity of .alpha.-AL.sub.2O.sub.3 is about 33
W/mK.sup.-1 at 25.degree. C. Thus, .alpha.-AL.sub.2O.sub.3 may be
used as a material for the lamp cover 60.
[0063] However, another example of light-transmitting material may
be used, as the lamp cover 60 is not limited to alumina. For
example, Lead Lanthanum Zirconate titanate (PLZT) having an
optoelectronic property and used as an optical communication
material, and CaF.sub.2, Y.sub.2O.sub.3, YAG, and polycrystalline
ALON, MgAl.sub.2O.sub.4, or the like that are high quality
transparent ceramic materials having a high cubic crystal, may be
used as materials for the lamp cover 60. ALON is formed by
adjusting a composition ratio of Al.sub.2O.sub.3 and AlN, and an
addition amount of Y.sub.2O.sub.3, BN, CaO, or MgO, which is used
as a sintering agent, and in this regard, it is possible to find a
material having high light-transmittance and high thermal
conductivity according to the composition ratio and the addition
amount. A composition ratio of ALON developed by Surmet Corporation
is AL.sub.23-1/3xO.sub.27+xN.sub.5-x (0.49<x<2), a thermal
conductivity of ALON is 9.7 W/mK.sup.-1 at 75.degree. C., a thermal
conductivity of MgAl.sub.2O.sub.4 is 25 W/mK.sup.-1 at 25.degree.
C., and light transmittance of MgAl.sub.2O.sub.4 having a thickness
of 4 mm is 76% of wavelength light with 650 nm.
[0064] In order to facilitate a heat transmittance between the heat
radiation unit 30 and the lamp cover 60, the heat radiation unit 30
and the lamp cover 60 may contact each other. As illustrated in
FIG. 7, a cover contacting part 34 that contacts and covers the
side surface 64 of the lamp cover 60 may be formed at an upper
portion of the heat radiation unit 30. By doing so, heat may be
maximally transferred from the heat radiation unit 30 to the lamp
cover 60.
[0065] Also, the heat radiation unit 30 may further include a heat
radiation ring 35 connected to the heat radiation body 32, the heat
radiation pin 33, and the cover contacting part 34.
[0066] FIG. 8 is a diagram illustrating a structure of the heat
radiation unit 30 in the light-emitting device lamp 100 of FIG. 1.
As illustrated in FIG. 8, the heat radiation body 32, the heat
radiation pin 33, and the cover contacting part 34 are connected to
each other via the heat radiation ring 35. By doing so, heat is
uniformly distributed to an entire region of the heat radiation
unit 30. Also, in order to activate air convection between the heat
radiation pin 33 and the cover contacting part 34, the heat
radiation ring 35 may have a plurality of openings 76 that
correspond to spaces between the heat radiation pins 33.
[0067] Alternatively, the lamp cover 60 may be formed by forming a
thermal conductive layer on a common cover.
[0068] FIG. 9 is a cross-sectional view of a lamp cover 80
according to an exemplary embodiment. As illustrated in FIG. 9, the
lamp cover 80 may include a cover 82 formed of a light-transmitting
material, and a thermal conductive layer 84 having one or more
layers and formed on an outer circumference of the cover 82. The
thermal conductive layer 84 contacts the cover contacting part 34
of the heat radiation unit 30. By doing so, a heat transmittance
from the heat radiation unit 30 to the lamp cover 80 is achieved by
a direct contact between the thermal conductive layer 84 and the
heat radiation unit 30. In order to increase a heat transmittance
area, as illustrated in FIG. 9, the thermal conductive layer 84 may
be formed to a projection of the lamp cover 80, and the projection
may be in surface contact with the second coupling groove 75.
[0069] Heat that is generated by the power circuit unit 70 may be
delivered to the heat radiation unit 30, because the housing 40 is
formed of a thermal conductive material and a contact area between
the housing 40 and the heat radiation unit 30 is increased. Also,
by forming the lamp cover 80 with a thermal conductive material and
by increasing a contact area between the heat radiation unit 30 and
the lamp cover 80, the lamp cover 80 may also perform a heat
radiation function. By doing so, without employing a compulsory
cooling method using a fan or the like, it is possible to implement
the light-emitting device lamp 100 having a high efficiency and a
long lifetime, and satisfying a specification of a traditional
lighting appearance.
[0070] In the aforementioned exemplary embodiments, a
light-emitting device lamp for replacing a halogen lamp is
described as an example but the scope of the one or more exemplary
embodiments are not limited thereto. Thus, it is obvious that the
aforementioned exemplary embodiments may also be applied to an
incandescent-type light-emitting device lamp.
[0071] In a light-emitting device lamp according to the one or more
exemplary embodiments, a housing is formed of a thermal conductive
material, so that heat generated by the housing is delivered to a
heat radiation unit.
[0072] Also, by maximally increasing the contact area between the
housing and the heat radiation unit, a heat radiation performance
may be improved.
[0073] Also, because a lamp cover is formed of a thermal conductive
material, the lamp cover may also perform a heat radiation
function.
[0074] While exemplary embodiments have been particularly shown and
described, it will be understood by those of ordinary skill in the
art that various changes in form and details may be made therein
without departing from the spirit and scope of the present
invention as defined by the following claims.
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